Currently, there are about 30 recognized species containing 47 serogroups of Legionella. Present serological detection methods are based on about 48 serogroup specific antigens which require about 48 serogroup specific antisera. Sampson et al. (J. Clin. Micro., 23:92-99, 1986) described a 58-kilodalton (later 60-kilodalton) protein antigen that was present in all Legionella species examined and which was found to be immunogenic in humans, reacting with serum from 100% of the culture-confirmed cases of legionellosis that were tested. Antibody to this protein was considered as a possible probe in immunological procedures to detect all species in the genus Legionella. Polyclonal rabbit antisera to the 60-kilodalton protein was produced by the method of Plikaytis et al. (J. Clin. Micro., 25:2080-2084, 1987) for use as a detection reagent. To achieve specificity to the Legionella genus, the polyclonal antisera had to be sequentially absorbed with three heterologous organisms, thereby significantly decreasing the potency of the antisera. In contrast, the monoclonal antibodies produced by the hybridoma cell lines are not subject to the variabilities encountered in the production of polyclonal antisera.
A variety of diagnostic techniques for detection of Legionnaire's disease are known. Patent No. 87/05609 issued to Hoffman describes monoclonal antibodies for the detection of Legionella species. However, these antibodies have cross-reactivity with the bacteria of other genus.